ABSTRACT The indiscriminate use of pesticides on grape crops is harmful for consumers´ healthin “in natura” consumption and in the ingestion of wine and grape juice. During winemaking, a rapid and efficient fermentation stage is critical to avoid proliferation of contaminating microorganisms and to guarantee the product´s quality. Polymerase chain reaction (PCR) has the advantage of detecting these contaminants in the early stages of fermentation. However,this enzymatic reaction may also be susceptible to specific problems, reducing its efficiency. Agricultural practices, such as fungicide treatments, may be a source of PCR inhibiting factors and may also interfere in the normal course of fermentation.The action of the pesticides captan and folpet on PCR and on yeast metabolism was evaluated, once these phthalimide compounds are widely employed in Brazilian vineyards. DNA amplification was only observed at 75 and 37.5 µg/mL of captan concentrations, whereas with folpet, amplification was observed only in the two lowest concentrations tested (42.2 and 21.1µg/mL).Besides the strong inhibition on Taq polymerase activity, phthalimides also inhibited yeast metabolism at all concentrations analyzed.Grape must containing captan and folpet residues could not be transformed into wine due to stuck fermentation caused by the inhibition of yeast metabolism. Non-compliance with the waiting period for phthalimide fungicides may result in financial liabilities to the viticulture sector.The use of yeasts with high fungicide sensitivity should be selected for must fermentation as a strategy for sustainable wine production and to assure that products comply with health and food safety standards.

The purpose of this work was to study a rapid yeast DNA extraction by boiling and freeze-thawing processes without using chemical reagents or any purification procedures, to obtain a high grade PCR-product. A specific DNA fragment of the 18S region of Dekkera bruxellensis and Saccharomyces cerevisiae was chosen. The described boiling and freeze-thawing protocols generated the PCR-grade product preparations and could be used to process many samples. The amplification of the fragments could be observed after 30 and 35 cycles. These processes of extraction without using any kind of chemical reagents, especial water, and purification procedures proved to be efficient, reproducible, simple, fast, and inexpensive.

O objetivo deste trabalho foi avaliar o efeito de tratamentos pré-colheita sobre a ocorrência de podridões pós-colheita e sobre os atributos de qualidade de framboesas (Rubus idaeus L.) 'Heritage'. As frutas foram pulverizadas com um dos seguintes tratamentos: água destilada (controle), 6 g L-1 de quitosana, 100 mg L-1 de dióxido de cloro, Bacillus amyloliquefaciens, Curtobacterium pusillum ou Saccharomyces cerevisiae. Foram realizadas colheitas aos 3, 7 e 14 dias após a aplicação dos tratamentos. Após cada uma das colheitas, realizadas no estádio de maturação comercial (coloração rosa), as frutas foram inoculadas individualmente com suspensão de conídios (2x10(5) conídios mL-1) de Botrytis cinerea ou Rhizopus stolonifer. As frutas foram mantidas a 12±0,5ºC por sete dias e avaliadas quanto à incidência de podridões e quanto aos principais atributos de qualidade. Bacillus amyloliquefaciens, C. pusillum e S. cerevisiae proporcionaram menor área abaixo da curva de progresso da incidência das podridões por Botrytis e Rhizopus. Os agentes de controle biológico avaliados não interferem negativamente sobre os atributos de qualidade das frutas, e, portanto, são alternativas potenciais no controle de podridões pós-colheita de framboesas.

The objective of this work was to evaluate the effect of pre-harvest treatments on post-harvest decay and on quality of 'Heritage' raspberries (Rubus idaeus L.). Fruit were sprayed with one of the following treatments: distilled water (control), 6 g L-1 of chitosan, 100 mg L-1 of chlorine dioxide solution, Bacillus amyloliquefaciens, Curtobacterium pusillum or Saccharomyces cerevisiae suspensions. Harvest was done at 3, 7, and 14 days after spray treatment. After each harvest, at commercial maturity (when fruit were pink), fruit were individually inoculated with conidial suspension (2x10(5) conidia mL-1) of Botrytis cinerea or Rhizopus stolonifer. Fruit were kept at 12±0.5ºC for seven days and were evaluated for decay and main quality attributes. Bacillus amyloliquefaciens, C. pusillum, and S. cerevisiae provided smaller area under disease progress curve of decays caused by Botrytis and Rhizopus. The biological control agents evaluated do not adversely affect fruit quality attributes, and, therefore, are potential alternatives to control post-harvest decay of raspberries.

The aim of this work was to study the production of functional protein in yeast culture. The cells of Saccharomyces cerevisiae Embrapa 1B (K+R+) killed a strain of Saccharomyces cerevisiae Embrapa 26B (K-R-)in grape must and YEPD media. The lethal effect of toxin-containing supernatant and the effect of aeration upon functional killer production and the correlation between the products of anaerobic metabolism and the functional toxin formation were evaluated. The results showed that at low sugar concentration, the toxin of the killer strain of Sacch. cerevisiae was only produced under anaerobic conditions . The system of killer protein production showed to be regulated by Pasteur and Crabtree effects. As soon as the ethanol was formed, the functional killer toxin was produced. The synthesis of the active killer toxin seemed to be somewhat associated with the switch to fermentation process and with concomitant alcohol dehydrogenase (ADH) activity.

The aim of this work was to evaluate the influence of Brettanomyces custersianus on the metabolic activity of Saccharomyces cerevisiae during the tumultuous stage of wine production. The Cabernet Sauvignon grape must with the skin was inoculated with individual cultures of Sacch. cerevisiae and with mixed cultures of Sacch. cerevisiae and Br. custersianus. During the 6-day tumultuous phase of fermentation, the highest ethanol production and the highest sugar consumption were obtained with the strains without B. custersianus. Fermentations carried out with the addition of Brettanomyces metabolites, acetic acid and 4-ethylphenol, showed that only the former inhibited the growth of both Sacch. cerevisiae strains used. In some cases, Br. custersianus could affect the rate higher alcohols production and their final concentrations during the tumultuous phase of vinification.

Diversos microrganismos secretam substâncias com alta afinidade por ferro. Estas moléculas, sideróforos, transportam ferro para o interior das células. Como a produção destas moléculas depende da composição do meio, foi avaliada a influência do extrato de levedura (FYE), proveniente de resíduo de cervejaria, com e sem adição de sais minerais, sobre o crescimento de Pseudomonas fluorescens e sobre a formação de pigmento fluorescente verde-amarelado (YGFP). Observou-se que (i) FYE com sacarose (G7) e o extrato de levedura comercial (CYE) possuem um pico bem definido próximo a 260 nm; (ii) FYE, mas não CYE, promove alta formação de YGFP. Os meios de King's, usados para detectar a formação de sideróforo, se comportaram como indutores expressivamente mais fracos de YGFP que o meio FYE. Embora FYE e CYE possam ser usados para o crescimento de P. fluorescens, apenas FYE pode ser usado como meio para a detecção de linhagens formadoras de YGFP.

A medium was prepared from brewery waste yeast with and without mineral salts to study growth and yellow-green fluorescent pigment production (YGFP) by Pseudomonas fluorescens. The King's medium used for detection of siderophore production were expressively weaker inductors of YGFP formation when compared to FYE medium. Although FYE and CYE could be used for growth of P. fluorescens, only FYE was an attractive medium for detection of YGFP strain producers.

Este trabalho teve por objetivo avaliar as transformações fisiológicas que ocorrem na uva 'Isabel' (Vitis labrusca L.), em diferentes condições de armazenamento. As uvas foram conservadas em temperatura ambiente (25°C) e sob refrigeração (4°C) e mantidas em dessecadores com aplicação de vácuo (-60kPa), no início do processo de armazenamento, e sem aplicação de vácuo. Os metabólitos produzidos foram analisados por cromatografia gás-líquida. Foi utilizado o delineamento experimental inteiramente casualidade, com duas repetições. A refrigeração reduziu a produção de etanol e de metanol. A formação de acetato de etila não foi afetada pelo vácuo ou pela temperatura isoladamente, mas depende da interação desses dois falares. A produção de etanol dependeu da interação temperatura-vácuo. A aplicação de vácuo aumentou a produção de etanol em temperatura ambiente. A refrigeração diminuiu a quantidade de bagas danificadas e a aplicação do vácuo teve um efeito oposto. Os resultados obtidos com a cultivar Isabel sugerem que o procedimento de aplicar vácuo m início do processo de armazenamento de uva pode induzir dano físico às bagas até mesmo sob refrigeração e que, pela correlação observada, a deterioração da uva Isabel armazenada pode ser monitorada, analisando a concentração de etanol, metanol e eternal.

In this research, the physiological transformations of 'Isabella' (Vitis labrusca L) grapes aí different storage conditions were examined. The grapes were stored at 25°C (nonchilled) and 4°C (chilled) crnd maintained m a desiccator with vacuum (-60kPa) appiicatíon at lhe beginning of the storage process and without vacuum appiicatíon. The metabolites produced were quantitativety determined by gas-liquid chromatography and statistically analysed using a completely randomized design with two repetitions. The chilling storage reduced the production of both ethanol and methanol. The ethyl acetato formation did not depena on the individual effects of vacuum and temperature but is affected by the interaction ofthese two factors. The ethanol production was increased by vacuum at room temperature and by the interaction temperature-vacuum. The chilling storage diminished the amount of damaged berries and the vacuum had an opposite effect. The results obtained with the cultivar Isabella suggest that the procedure of appiying vacuum at the beginning ofthe grape storage process may induce physical damage even ai chilling storage. The correlation studies show that the deterioration of stored Isabella table grapes can be readily monitored byfollowing the methanol, ethanol and ethanal production.